A valve assembly which opens and closes a passageway through which fluid flows is usually used in a variety of systems within a vehicle. The valve assembly is generally actuated by an electronic actuator. The performance of the valve assembly is determined by its ability to accurately and rapidly open and close a passageway. In particular, control over the open ratio of a throttle valve used in a vehicle is an important factor since the open ratio of the throttle valve is influential in determining the power of an engine. The open ratio of the valve assembly is measured and controlled by a sensor. When the supply of electric power is shut off, there is a danger in that the open ratio of the valve assembly does not return to the initial position. This danger is significant especially for a throttle valve used in a vehicle.
A throttle device applied to an internal combustion engine such as a vehicular engine is a device which is mechanically connected to an accelerator pedal of a vehicle. When a driver steps on the accelerator pedal while the vehicle is traveling, the throttle device operates a throttle valve, thereby supplying as much air as required for accelerating the vehicle to the engine.
Among such throttle devices, there is a throttle device which is not provided with a separate bypass passageway on an intake passage. This throttle device is configured to automatically open a throttle valve to a preset angle to provide a minimum amount of air such that the engine does not stop, in response to a signal from an engine control system when the vehicle is not accelerated during traveling or when the vehicle is idling such as during startup.
A throttle device of the related art has a semi-electronic configuration in which a throttle valve is automatically opened under the control of an engine control system in an idling state and is opened in response to force with which a driver steps on the accelerator pedal being mechanically delivered to a throttle valve shaft.
In addition, a throttle position sensor, which generates an electrical signal by detecting the angle of rotation of the throttle valve, is provided at a preset position inside the throttle body. A motor which is disposed at one side of the throttle body serves to open the throttle valve such that a minimum amount of air required for the operation of the engine is introduced. A connector is provided at a preset position outside the throttle body.
In this throttle device of the related art, the throttle valve is opened when the motor operates in response to an electrical signal from the engine control system in the idling state. However, in the acceleration state, the throttle valve shaft and the throttle valve rotate in response to the rotation of a pulley connected to the accelerator pedal, thereby degrading the performance and drivability of a vehicle.
In addition, in the throttle device of the related art, the throttle position sensor which generates a signal by detecting the angle of the throttle valve and the connector are mounted on the throttle body. The pulley, which rotates in cooperation with the accelerator pedal, and the return spring are disposed outside the throttle body. Thus, there are problems in that assembly performance is very poor and the size of an article increases.
Furthermore, in the throttle device of the related art, the minimum angle of opening of the throttle valve is pre-calculated in order to adjust the minimum amount of air required for the idling state and then is mechanically fixed by, for example, welding, in a fabrication process. In this case, when the amount of air is set, the amount of air changes significantly due to errors in the machining and assembly of parts, thereby making it difficult to accurately set the minimum amount of air, which is problematic.
A prior art related to this is disclosed in Korean Laid-Open Patent Publication No. 1998-0083373 (published Dec. 5, 1998, titled: “ELECTRICALLY CONTROLLED DEVICE FOR OPENING AND CLOSING THROTTLE”).